Missile decoy



1960 D. D. MUSGRAVE 2,957,417

MISSILE DECOY Filed NOV. 4, 1958 INVENTOR United States Patent O2,957,417 .nnssmnnncoY Daniel D. Musgrave, 8201 Caraway St., Cabin John,Md. Filed Nov. 4, 1958, Ser. No. 771,845 2 Claims. (Cl. 102-50) Thisinvention relates to a decoy system for use on a missile or rocket. Itwill be disclosed herein as applied to an air-to-air missile but it isnot limited to such use. The range of utility of the device will dependon tactical considerations.

It is well known that many missiles are capable of homing on objectswhich emit infra-red radiation. That such missiles must have tunnelvision is obvious, otherwise they might seek the sun. If there be morethan one radiating object within the homing cone of the missile, whatpoint it will target on will depend on the intensity, distance to, anddistribution of the several radiant sources.

The role of the missile in air combat is to destroy the enemy plane. Inthis it seems to have supplanted the machine gun. The machine guns ofbombing aricraft were considered defensive weapons whose purpose was topermit the plane to fight oil interceptors and continue on to the bombtarget. To increase their defensive ability, these machine guns weresometimes supplied with Headlight ammunition which, in addition to itsnormal ballistic effect, had an adverse morale effect on the pilots ofattacking interceptors because its trace was visible from the directionof the target.

The primary object of this invention is to increase the effectiveness ofcertain types of missiles by giving them defensive capabilities inaddition to their offensive potential.

Another object is to strengthen the defense of the large bombing planeby providing a missile which may act as a decoy at the critical timewhen the bomber is being attacked by missile-armed interceptors.

Another object is to intensify the attraction which certain missiles orrockets may exert for homing guided missiles approaching from a certaindirection.

Other objects of the invention will be apparent from the description ofthe ivention as hereinafter set forth in detail and from the drawingsmade a part thereof in which:

Figure l is a perspective view of the invention as ap-' plied to therear portion of a missile.

Figure 2 is a section view of the invention taken in the plane indicatedby line 2-2 in Figure 1.

Figure 3 is a schematic view to show the relationship of certaintechnical and tactical characteristics of missiles and planes in anair-to-air combat situation.

Referring to Figure 1 more in detail, there is shown a missile 1 havingrear stabilizing fins 3 afiixed to it as by welding. The number ofstabilizing fins 3 is immaterial but in this case it happens to be four.To the fins 3 is aflixed, as by welding, a shroud 5 which in this caseconsists of two quarter circle portions, each affixed to the extremitiesof a pair of fins. Missile 1 has a typical motor orifice 7 which liesalong its longitudinal axis.

The internal surface of shroud 5 is indicated by numeral Referring nowto Figure 2 it will be noted that shroud 5 is shaped as the outerportion of a theoretical paraboloid, the missing portion of which isindicated by broken "ice 2 line 11. The principal focus 13 of thetheoretical paraboloid is .located immediately behind .motor orifice 7.The internal surface 9 of shroud 5 is polished to form a reflector whichreceives incident rays of infra-red or otherradiation from thevicinityof principal focus 'l3iand reflects them in the-direction towardwhich the missile is fiying. -A pair of reflectedrays areshown at 15 and17.

The missiles course may be set in the well known manner by guidance fins19.

In Figure 3 there is shown schematically a pursuit situation involving abomber 50 and an interceptor 59, both armed with missiles. It will beassumed that both planes travel at the same speed and release theirmissiles simultaneously. It will also be assumed that both missiles haveequal performance capabilities.

Bomber 50 is assumed to have engines 51, 52, 53 and 54, with interceptor59 as a vertex, define an angle, 58, which will tend to increase as thedistance from the vertex to the outboard engines is decreased. We willassume that interceptor 59 is armed with, and launches, a missile, 57 inan attempt to destroy bomber 50.

From an extreme range missile 57 will find the included angle betweenengines 51 and 54 small, and will be unable to distinguish separateradiation sources. As missile 57 approaches target the included anglebetween engines 51 and 54 will exceed its filed of vision and it willbecome selective and narrow its choice to include the more intenseradiation sources. When it strikes a multiengine target presumably itwill hit the hottest engine.

Bomber 50 is assumed to be armed with, and has launched a missile 56,with interceptor 59 as its target. Missile 56 is assumed to be equippedwith the decoy apparatus shown in Figs. 1 and 2. Missiles 56 and 57 werereleased at the same time but 57 approaches target first because itsacceleration is added to the speed of interceptor 59. Missile 56 is at adisadvantage since its acceleration must overcome the negative speed ofbomber 50. Accordingly, they do not approach each other midway to targetbut somewhat as shown in Figure 3.

Since missiles are driven by heat engines they themseleves are radiationsources, but the radiation is normally dissipated in all directions withthe least going to the front. By means of its decoy apparatus missile 56directs an intense beam of rays forward causing missiles 57 to home onits and both missiles are destroyed. If either plane carries a secondmissile it may launch now to try for a kill.

As stated above the range of utility of this invention will depend ontactical considerations. The example cited is but one of a vast numberof possible combinations of course and speed for the opposing aircraft.The missiles too may vary in speed, fuzing, homing, programing andburnout time. If both combatants use missiles having a decoy system newtactics may result.

It is desired to point out that changes may be made without departingfrom the spirit of the invention. The decoy might be applied to anunguided rocket. The shroud may form a complete circle about the fins,which may be of the folding or of the sliding type. The radiant sourceis not a true point source and the reflector might be conic or concave.

What I claim is:

1. On a missile having stabilizing fins and a reaction thrust motor, adecoy system comprising a shroud fixed to the fins of said missilehaving an internal reflective surface of partial parabolic shape withits principal focus subtantially on the axis of said motor and adaptedfor directing radiation from said motor in a direction opposite to thethrust of said motor.

2. On a missile having stabilizing fins and a reaction thrust motor, adecoy system comprising a shroud fixed to the fins of said missilehaving an internal concave reflective surface with its principal focussubstantially on the axis of said motor and adapted for directingradiation from said motor in a direction opposite to the thrust of saidmotor.

References Cited in the file of this patent UNITED STATES PATENTS2,510,147 Skinner June 6, 1950 2,642,777 Bradler June 23, 1953 2,737,356Varian et a1 Mar. 6, 1956 OTHER REFERENCES Klass, P. 1.: Exclusive.Report on Infrared, reprinted from Aviation Week, March 4; 11, and 18,1957, pub- 10 lished by McGraw-Hill Publishing Company.

